【发布时间】：2019-04-14 12:50:52
【问题描述】：
我目前正在使用 GUI 开发计算器。
这就是我的意思以及它应该如何工作。
- 在输入一系列数字运算符号后，用户可以 点击： ‘=’，在这种情况下，计算器必须显示： i. ‘=’ 第二个数字的最后一个数字后的符号 ii.操作的结果，在一个新的行上 iii。之后输入的任何其他内容 ‘=’ 符号是新计算的一部分，必须显示在 单独一行
例如用户点击：123.45+456.2=1”。屏幕应如下所示：
123.45+ 由用户输入
456.2= 由用户输入
579.65 由您的程序计算并显示
这就是我希望计算器显示先前输入并在单击数学运算符后转到新行的方式。请注意，我也尝试过追加，但没有成功。
代码：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
public class CalculatorFrame extends JFrame {
/**
* All the buttons that will be used in the calculator have been initialized
*/
private JButton button1;
private JButton button2;
private JButton button3;
private JButton button4;
private JButton button5;
private JButton button6;
private JButton button7;
private JButton button8;
private JButton button9;
private JButton button0;
private JButton buttonEqual;
private JButton buttonDot;
private JButton buttonClearLast;
private JButton buttonClearAll;
private JButton buttonAdd;
private JButton buttonSub;
private JButton buttonMul;
private JButton buttonDiv;
private JTextArea textArea;
private JScrollPane scrollPane;
private JTextField textFieldResult;
String display = "";
private double TEMP;
private double equalTemp;
private int clearLastChar = 1;
Boolean additionBoolean = false;
Boolean subtractionBoolean = false;
Boolean multiplicationBoolean = false;
Boolean divisionBoolean = false;
public CalculatorFrame(){
JPanel panel2 = new JPanel();
panel2.setLayout(new GridLayout(1,1));
panel2.add(buttonClearLast = new JButton ("Clear Last"));
panel2.add(buttonClearAll = new JButton ("Clear All"));
add(panel2, BorderLayout.PAGE_START);
JPanel panel3 = new JPanel();
textArea = new JTextArea();
scrollPane = new JScrollPane(textArea);
scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
add(scrollPane);
add(panel3, BorderLayout.AFTER_LAST_LINE);
JPanel panel1 = new JPanel();
panel1.setLayout(new GridLayout(4,4));
panel1.add(button7 = new JButton ("7"));
panel1.add(button8 = new JButton ("8"));
panel1.add(button9 = new JButton ("9"));
panel1.add(buttonAdd = new JButton ("+"));
panel1.add(button4 = new JButton ("4"));
panel1.add(button5 = new JButton ("5"));
panel1.add(button6 = new JButton ("6"));
panel1.add(buttonSub = new JButton ("-"));
panel1.add(button1 = new JButton ("1"));
panel1.add(button2 = new JButton ("2"));
panel1.add(button3 = new JButton ("3"));
panel1.add(buttonMul = new JButton ("*"));
panel1.add(button0 = new JButton ("0"));
panel1.add(buttonDot = new JButton ("."));
panel1.add(buttonEqual = new JButton ("="));
panel1.add(buttonDiv = new JButton ("/"));
add(panel1, BorderLayout.PAGE_END);
pack();
buttonClearLast.addActionListener(new ListenToClearLast());
buttonClearAll.addActionListener(new ListenToClearAll());
button1.addActionListener(new ListenToOne());
button2.addActionListener(new ListenToTwo());
button3.addActionListener(new ListenToThree());
button4.addActionListener(new ListenToFour());
button5.addActionListener(new ListenToFive());
button6.addActionListener(new ListenToSix());
button7.addActionListener(new ListenToSeven());
button8.addActionListener(new ListenToEight());
button9.addActionListener(new ListenToNine());
button0.addActionListener(new ListenToZero());
buttonAdd.addActionListener(new ListenToAdd());
buttonSub.addActionListener(new ListenToSub());
buttonMul.addActionListener(new ListenToMul());
buttonDiv.addActionListener(new ListenToDiv());
buttonEqual.addActionListener(new ListenToEqual());
buttonDot.addActionListener(new ListenToDot());
}
/**
* This is where the action listener listens to all the button being pressed
* Once heard, it will show case it to the TextArea of the calculator.
*/
public class ListenToOne implements ActionListener{
public void actionPerformed(ActionEvent e){
// display = textArea.getText();
textArea.append("1");
}
}
public class ListenToTwo implements ActionListener{
public void actionPerformed(ActionEvent e){
// display = textArea.getText();
textArea.append("2");
}
}
public class ListenToThree implements ActionListener{
public void actionPerformed(ActionEvent e){
// display = textArea.getText();
textArea.append("3");
}
}
public class ListenToFour implements ActionListener{
public void actionPerformed(ActionEvent e){
// display = textArea.getText();
textArea.append("4");
}
}
public class ListenToFive implements ActionListener{
public void actionPerformed(ActionEvent e){
// display = textArea.getText();
textArea.append("5");
}
}
public class ListenToSix implements ActionListener{
public void actionPerformed(ActionEvent e){
// display = textArea.getText();
textArea.append("6");
}
}
public class ListenToSeven implements ActionListener{
public void actionPerformed(ActionEvent e){
// display = textArea.getText();
textArea.append("7");
}
}
public class ListenToEight implements ActionListener{
public void actionPerformed(ActionEvent e){
// display = textArea.getText();
textArea.append("8");
}
}
public class ListenToNine implements ActionListener{
public void actionPerformed(ActionEvent e){
// display = textArea.getText();
textArea.append("9");
}
}
public class ListenToZero implements ActionListener{
public void actionPerformed(ActionEvent e){
// display = textArea.getText();
textArea.append("0");
}
}
// This is used for decimal points.
// If the dot button is clicked, it will display "."
public class ListenToDot implements ActionListener{
public void actionPerformed(ActionEvent e){
// display = textArea.getText();
textArea.append(".");
}
}
// The next 4 methods are for the basic operators.
// If any of the operator button is clicked, it would set it's boolean value to true and
// tell the program which operation to perform
public class ListenToAdd implements ActionListener{
public void actionPerformed (ActionEvent e){
TEMP = Double.parseDouble(textArea.getText());
textArea.append("+\n");
additionBoolean = true;
}
}
public class ListenToSub implements ActionListener{
public void actionPerformed (ActionEvent e){
TEMP = Double.parseDouble(textArea.getText());
textArea.setText("- \n");
subtractionBoolean = true;
}
}
public class ListenToMul implements ActionListener{
public void actionPerformed (ActionEvent e){
TEMP = Double.parseDouble(textArea.getText());
textArea.setText("* \n");
multiplicationBoolean = true;
}
}
public class ListenToDiv implements ActionListener{
public void actionPerformed (ActionEvent e){
TEMP = Double.parseDouble(textArea.getText());
textArea.setText("/ \n");
divisionBoolean = true;
}
}
// This ListenToEqual method does all the calculation
// First, the program is checking what kind of calculation to perform by comparing it's boolean values.
// Once that is done, it will get the previous input from the user using the getText method and add/sub/mul/div with the new value
// The output will be displayed in the text area.
public class ListenToEqual implements ActionListener{
public void actionPerformed (ActionEvent e){
equalTemp = Double.parseDouble(textArea.getText());
if (additionBoolean == true)
equalTemp = equalTemp + TEMP;
else if (subtractionBoolean == true)
equalTemp = TEMP - equalTemp;
else if (multiplicationBoolean == true)
equalTemp = equalTemp * TEMP;
else if (divisionBoolean == true)
equalTemp = TEMP / equalTemp;
textArea.append(Double.toString(equalTemp));
// textArea.setText("1");
additionBoolean = false;
subtractionBoolean = false;
multiplicationBoolean = false;
divisionBoolean = false;
}
}
public class ListenToClearAll implements ActionListener{
public void actionPerformed (ActionEvent e){
textArea.setText("");
additionBoolean = false;
subtractionBoolean = false;
multiplicationBoolean = false;
divisionBoolean = false;
TEMP = 0;
equalTemp = 0;
}
}
public class ListenToClearLast implements ActionListener{
public void actionPerformed (ActionEvent e){
String currentChar = textArea.getText();
String currentCharMinus = currentChar.substring(0,currentChar.length()-clearLastChar);
textArea.setText(currentCharMinus);
}
}
}
这就是我的计算器的外观。
计算器：
关于如何显示上面示例中的输出的任何帮助。
谢谢。
【问题讨论】：
标签： java user-interface append jtextarea